/*
 * $Id: JSONParser.java,v 1.1 2006/04/15 14:10:48 platform Exp $
 * Created on 2006-4-15
 */
package org.json.simple.parser;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;

/**
 * Parser for JSON text. Please note that JSONParser is NOT thread-safe.
 * 
 * @author FangYidong<fangyidong@yahoo.com.cn>
 */
public class JSONParser {
    public static final int S_INIT = 0;
    public static final int S_IN_FINISHED_VALUE = 1;// string,number,boolean,null,object,array
    public static final int S_IN_OBJECT = 2;
    public static final int S_IN_ARRAY = 3;
    public static final int S_PASSED_PAIR_KEY = 4;
    public static final int S_IN_PAIR_VALUE = 5;
    public static final int S_END = 6;
    public static final int S_IN_ERROR = -1;

    private LinkedList<Object> handlerStatusStack;
    private Yylex lexer = new Yylex((Reader) null);
    private Yytoken token = null;
    private int status = S_INIT;

    private int peekStatus(LinkedList<Object> statusStack)
    {
        if (statusStack.size() == 0)
            return -1;
        Integer status = (Integer) statusStack.getFirst();
        return status.intValue();
    }

    /**
     * Reset the parser to the initial state without resetting the underlying
     * reader.
     * 
     */
    public void reset()
    {
        token = null;
        status = S_INIT;
        handlerStatusStack = null;
    }

    /**
     * Reset the parser to the initial state with a new character reader.
     * 
     * @param in
     *            - The new character reader.
     * @throws IOException
     * @throws ParseException
     */
    public void reset(Reader in)
    {
        lexer.yyreset(in);
        reset();
    }

    /**
     * @return The position of the beginning of the current token.
     */
    public int getPosition()
    {
        return lexer.getPosition();
    }

    public Object parse(String s) throws ParseException
    {
        return parse(s, (ContainerFactory) null);
    }

    public Object parse(String s, ContainerFactory containerFactory) throws ParseException
    {
        StringReader in = new StringReader(s);
        try
        {
            return parse(in, containerFactory);
        }
        catch (IOException ie)
        {
            /*
             * Actually it will never happen.
             */
            throw new ParseException(-1, ParseException.ERROR_UNEXPECTED_EXCEPTION, ie);
        }
    }

    public Object parse(Reader in) throws IOException, ParseException
    {
        return parse(in, (ContainerFactory) null);
    }

    /**
     * Parse JSON text into java object from the input source.
     * 
     * @param in
     * @param containerFactory
     *            - Use this factory to createyour own JSON object and JSON
     *            array containers.
     * @return Instance of the following: org.json.simple.JSONObject,
     *         org.json.simple.JSONArray, java.lang.String, java.lang.Number,
     *         java.lang.Boolean, null
     * 
     * @throws IOException
     * @throws ParseException
     */
    @SuppressWarnings("unchecked")
    public Object parse(Reader in, ContainerFactory containerFactory) throws IOException, ParseException
    {
        reset(in);
        LinkedList<Object> statusStack = new LinkedList<Object>();
        LinkedList<Object> valueStack = new LinkedList<Object>();

        try
        {
            do
            {
                nextToken();
                switch (status)
                {
                    case S_INIT:
                        switch (token.type)
                        {
                            case Yytoken.TYPE_VALUE:
                                status = S_IN_FINISHED_VALUE;
                                statusStack.addFirst(new Integer(status));
                                valueStack.addFirst(token.value);
                                break;
                            case Yytoken.TYPE_LEFT_BRACE:
                                status = S_IN_OBJECT;
                                statusStack.addFirst(new Integer(status));
                                valueStack.addFirst(createObjectContainer(containerFactory));
                                break;
                            case Yytoken.TYPE_LEFT_SQUARE:
                                status = S_IN_ARRAY;
                                statusStack.addFirst(new Integer(status));
                                valueStack.addFirst(createArrayContainer(containerFactory));
                                break;
                            default:
                                status = S_IN_ERROR;
                        }// inner switch
                        break;

                    case S_IN_FINISHED_VALUE:
                        if (token.type == Yytoken.TYPE_EOF)
                            return valueStack.removeFirst();
                        else
                            throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);

                    case S_IN_OBJECT:
                        switch (token.type)
                        {
                            case Yytoken.TYPE_COMMA:
                                break;
                            case Yytoken.TYPE_VALUE:
                                if (token.value instanceof String)
                                {
                                    String key = (String) token.value;
                                    valueStack.addFirst(key);
                                    status = S_PASSED_PAIR_KEY;
                                    statusStack.addFirst(new Integer(status));
                                }
                                else
                                {
                                    status = S_IN_ERROR;
                                }
                                break;
                            case Yytoken.TYPE_RIGHT_BRACE:
                                if (valueStack.size() > 1)
                                {
                                    statusStack.removeFirst();
                                    valueStack.removeFirst();
                                    status = peekStatus(statusStack);
                                }
                                else
                                {
                                    status = S_IN_FINISHED_VALUE;
                                }
                                break;
                            default:
                                status = S_IN_ERROR;
                                break;
                        }// inner switch
                        break;

                    case S_PASSED_PAIR_KEY:
                        switch (token.type)
                        {
                            case Yytoken.TYPE_COLON:
                                break;
                            case Yytoken.TYPE_VALUE:
                                statusStack.removeFirst();
                                String key = (String) valueStack.removeFirst();
                                Map<String, Object> parent = (Map<String, Object>) valueStack.getFirst();
                                parent.put(key, token.value);
                                status = peekStatus(statusStack);
                                break;
                            case Yytoken.TYPE_LEFT_SQUARE:
                                statusStack.removeFirst();
                                key = (String) valueStack.removeFirst();
                                parent = (Map<String, Object>) valueStack.getFirst();
                                List<Object> newArray = createArrayContainer(containerFactory);
                                parent.put(key, newArray);
                                status = S_IN_ARRAY;
                                statusStack.addFirst(new Integer(status));
                                valueStack.addFirst(newArray);
                                break;
                            case Yytoken.TYPE_LEFT_BRACE:
                                statusStack.removeFirst();
                                key = (String) valueStack.removeFirst();
                                parent = (Map<String, Object>) valueStack.getFirst();
                                Map<String, Object> newObject = createObjectContainer(containerFactory);
                                parent.put(key, newObject);
                                status = S_IN_OBJECT;
                                statusStack.addFirst(new Integer(status));
                                valueStack.addFirst(newObject);
                                break;
                            default:
                                status = S_IN_ERROR;
                        }
                        break;

                    case S_IN_ARRAY:
                        switch (token.type)
                        {
                            case Yytoken.TYPE_COMMA:
                                break;
                            case Yytoken.TYPE_VALUE:
                                List<Object> val = (List<Object>) valueStack.getFirst();
                                val.add(token.value);
                                break;
                            case Yytoken.TYPE_RIGHT_SQUARE:
                                if (valueStack.size() > 1)
                                {
                                    statusStack.removeFirst();
                                    valueStack.removeFirst();
                                    status = peekStatus(statusStack);
                                }
                                else
                                {
                                    status = S_IN_FINISHED_VALUE;
                                }
                                break;
                            case Yytoken.TYPE_LEFT_BRACE:
                                val = (List<Object>) valueStack.getFirst();
                                Map<String, Object> newObject = createObjectContainer(containerFactory);
                                val.add(newObject);
                                status = S_IN_OBJECT;
                                statusStack.addFirst(new Integer(status));
                                valueStack.addFirst(newObject);
                                break;
                            case Yytoken.TYPE_LEFT_SQUARE:
                                val = (List<Object>) valueStack.getFirst();
                                List<Object> newArray = createArrayContainer(containerFactory);
                                val.add(newArray);
                                status = S_IN_ARRAY;
                                statusStack.addFirst(new Integer(status));
                                valueStack.addFirst(newArray);
                                break;
                            default:
                                status = S_IN_ERROR;
                        }// inner switch
                        break;
                    case S_IN_ERROR:
                        throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
                }// switch
                if (status == S_IN_ERROR)
                {
                    throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
                }
            } while (token.type != Yytoken.TYPE_EOF);
        }
        catch (IOException ie)
        {
            throw ie;
        }

        throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
    }

    private void nextToken() throws ParseException, IOException
    {
        token = lexer.yylex();
        if (token == null)
            token = new Yytoken(Yytoken.TYPE_EOF, null);
    }

    private Map<String, Object> createObjectContainer(ContainerFactory containerFactory)
    {
        if (containerFactory == null)
            return new JSONObject();
        Map<String, Object> m = containerFactory.createObjectContainer();

        if (m == null)
            return new JSONObject();
        return m;
    }

    private List<Object> createArrayContainer(ContainerFactory containerFactory)
    {
        if (containerFactory == null)
            return new JSONArray();
        List<Object> l = containerFactory.creatArrayContainer();

        if (l == null)
            return new JSONArray();
        return l;
    }

    public void parse(String s, ContentHandler contentHandler) throws ParseException
    {
        parse(s, contentHandler, false);
    }

    public void parse(String s, ContentHandler contentHandler, boolean isResume) throws ParseException
    {
        StringReader in = new StringReader(s);
        try
        {
            parse(in, contentHandler, isResume);
        }
        catch (IOException ie)
        {
            /*
             * Actually it will never happen.
             */
            throw new ParseException(-1, ParseException.ERROR_UNEXPECTED_EXCEPTION, ie);
        }
    }

    public void parse(Reader in, ContentHandler contentHandler) throws IOException, ParseException
    {
        parse(in, contentHandler, false);
    }

    /**
     * Stream processing of JSON text.
     * 
     * @see ContentHandler
     * 
     * @param in
     * @param contentHandler
     * @param isResume
     *            - Indicates if it continues previous parsing operation. If set
     *            to true, resume parsing the old stream, and parameter 'in'
     *            will be ignored. If this method is called for the first time
     *            in this instance, isResume will be ignored.
     * 
     * @throws IOException
     * @throws ParseException
     */
    public void parse(Reader in, ContentHandler contentHandler, boolean isResume) throws IOException, ParseException
    {
        if (!isResume)
        {
            reset(in);
            handlerStatusStack = new LinkedList<Object>();
        }
        else
        {
            if (handlerStatusStack == null)
            {
                isResume = false;
                reset(in);
                handlerStatusStack = new LinkedList<Object>();
            }
        }

        LinkedList<Object> statusStack = handlerStatusStack;

        try
        {
            do
            {
                switch (status)
                {
                    case S_INIT:
                        contentHandler.startJSON();
                        nextToken();
                        switch (token.type)
                        {
                            case Yytoken.TYPE_VALUE:
                                status = S_IN_FINISHED_VALUE;
                                statusStack.addFirst(new Integer(status));
                                if (!contentHandler.primitive(token.value))
                                    return;
                                break;
                            case Yytoken.TYPE_LEFT_BRACE:
                                status = S_IN_OBJECT;
                                statusStack.addFirst(new Integer(status));
                                if (!contentHandler.startObject())
                                    return;
                                break;
                            case Yytoken.TYPE_LEFT_SQUARE:
                                status = S_IN_ARRAY;
                                statusStack.addFirst(new Integer(status));
                                if (!contentHandler.startArray())
                                    return;
                                break;
                            default:
                                status = S_IN_ERROR;
                        }// inner switch
                        break;

                    case S_IN_FINISHED_VALUE:
                        nextToken();
                        if (token.type == Yytoken.TYPE_EOF)
                        {
                            contentHandler.endJSON();
                            status = S_END;
                            return;
                        }
                        else
                        {
                            status = S_IN_ERROR;
                            throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
                        }

                    case S_IN_OBJECT:
                        nextToken();
                        switch (token.type)
                        {
                            case Yytoken.TYPE_COMMA:
                                break;
                            case Yytoken.TYPE_VALUE:
                                if (token.value instanceof String)
                                {
                                    String key = (String) token.value;
                                    status = S_PASSED_PAIR_KEY;
                                    statusStack.addFirst(new Integer(status));
                                    if (!contentHandler.startObjectEntry(key))
                                        return;
                                }
                                else
                                {
                                    status = S_IN_ERROR;
                                }
                                break;
                            case Yytoken.TYPE_RIGHT_BRACE:
                                if (statusStack.size() > 1)
                                {
                                    statusStack.removeFirst();
                                    status = peekStatus(statusStack);
                                }
                                else
                                {
                                    status = S_IN_FINISHED_VALUE;
                                }
                                if (!contentHandler.endObject())
                                    return;
                                break;
                            default:
                                status = S_IN_ERROR;
                                break;
                        }// inner switch
                        break;

                    case S_PASSED_PAIR_KEY:
                        nextToken();
                        switch (token.type)
                        {
                            case Yytoken.TYPE_COLON:
                                break;
                            case Yytoken.TYPE_VALUE:
                                statusStack.removeFirst();
                                status = peekStatus(statusStack);
                                if (!contentHandler.primitive(token.value))
                                    return;
                                if (!contentHandler.endObjectEntry())
                                    return;
                                break;
                            case Yytoken.TYPE_LEFT_SQUARE:
                                statusStack.removeFirst();
                                statusStack.addFirst(new Integer(S_IN_PAIR_VALUE));
                                status = S_IN_ARRAY;
                                statusStack.addFirst(new Integer(status));
                                if (!contentHandler.startArray())
                                    return;
                                break;
                            case Yytoken.TYPE_LEFT_BRACE:
                                statusStack.removeFirst();
                                statusStack.addFirst(new Integer(S_IN_PAIR_VALUE));
                                status = S_IN_OBJECT;
                                statusStack.addFirst(new Integer(status));
                                if (!contentHandler.startObject())
                                    return;
                                break;
                            default:
                                status = S_IN_ERROR;
                        }
                        break;

                    case S_IN_PAIR_VALUE:
                        /*
                         * S_IN_PAIR_VALUE is just a marker to indicate the end
                         * of an object entry, it doesn't proccess any token,
                         * therefore delay consuming token until next round.
                         */
                        statusStack.removeFirst();
                        status = peekStatus(statusStack);
                        if (!contentHandler.endObjectEntry())
                            return;
                        break;

                    case S_IN_ARRAY:
                        nextToken();
                        switch (token.type)
                        {
                            case Yytoken.TYPE_COMMA:
                                break;
                            case Yytoken.TYPE_VALUE:
                                if (!contentHandler.primitive(token.value))
                                    return;
                                break;
                            case Yytoken.TYPE_RIGHT_SQUARE:
                                if (statusStack.size() > 1)
                                {
                                    statusStack.removeFirst();
                                    status = peekStatus(statusStack);
                                }
                                else
                                {
                                    status = S_IN_FINISHED_VALUE;
                                }
                                if (!contentHandler.endArray())
                                    return;
                                break;
                            case Yytoken.TYPE_LEFT_BRACE:
                                status = S_IN_OBJECT;
                                statusStack.addFirst(new Integer(status));
                                if (!contentHandler.startObject())
                                    return;
                                break;
                            case Yytoken.TYPE_LEFT_SQUARE:
                                status = S_IN_ARRAY;
                                statusStack.addFirst(new Integer(status));
                                if (!contentHandler.startArray())
                                    return;
                                break;
                            default:
                                status = S_IN_ERROR;
                        }// inner switch
                        break;

                    case S_END:
                        return;

                    case S_IN_ERROR:
                        throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
                }// switch
                if (status == S_IN_ERROR)
                {
                    throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
                }
            } while (token.type != Yytoken.TYPE_EOF);
        }
        catch (IOException ie)
        {
            status = S_IN_ERROR;
            throw ie;
        }
        catch (ParseException pe)
        {
            status = S_IN_ERROR;
            throw pe;
        }
        catch (RuntimeException re)
        {
            status = S_IN_ERROR;
            throw re;
        }
        catch (Error e)
        {
            status = S_IN_ERROR;
            throw e;
        }

        status = S_IN_ERROR;
        throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
    }
}
